JPH0353445B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] This invention relates to a turning device for a steam turbine.

[Prior art and its problems]

A steam turbine is in a uniform high temperature state during operation, but during the natural cooling process until complete cooling after shutdown, the rotor bends due to uneven temperatures above and below the turbine.

In general, turbines are required to be able to be restarted on the way to complete cooling, so in order to prevent rotor bending, low-speed turning can be performed after stopping. Low-speed turning methods include an electric type and a hydraulic type, but in both of these methods, the turning device main body is connected to a wheel provided on a turbine rotor via a gear train. Due to the structure, this wheel is normally placed outside the journal bearing, that is, on the shaft end side. This will be explained with reference to FIG. 1 is a turbine; 2 is a turbine rotor; a journal bearing 4 on a front bearing pedestal 3 and a journal bearing 6 on a rear bearing pedestal 5;
7 is the shaft end of the rotor. 8 is a front gland packing, and 9 is a rear gland packing. The turning device main body 10 is installed on the upper part of the rear bearing stand 5 and is connected to a rotor wheel 12 via a gear train 11. In this case, since the rotor wheel is located between the rear journal bearing 12 and the shaft end 7, the amount of overhang at the shaft end becomes longer, and the additional weight increases accordingly. This reduces the secondary critical speed in a single flexible rotor and further increases the sensitivity of the unbalance response at the shaft end, which is disadvantageous to rotor vibration. Therefore, when trying to arrange the rotor wheel between the rear gland packing 9 and the rear journal bearing 6, the turning device main body 10
The turning device 10 had to be moved closer to the turbine 1, and there was a problem that the turning device 10 interfered with the exhaust part of the turbine casing (not shown).

[Purpose of the invention]

In view of the above-mentioned circumstances, this idea was developed by leaving the turning device in the conventional position to avoid interference with the exhaust section of the turbine casing, and by locating the rotor wheel between the gland packing and the journal bearing. The purpose is to shorten the amount of overhang on the end 7 side and reduce the added weight.

[Key points of the invention]

The object of the present invention is to lengthen the gear shaft of the gear train interposed between the turning device main body and the rotor wheel so that the rotor wheel is placed between the gland packing and the journal bearing while the turning device main body remains in its conventional position. This is achieved by

[Embodiments of the invention]

FIG. 1 shows an embodiment of this invention, and FIG.
The difference from the figure is that the turning rotor wheel 6 is disposed between the rear gland packing 9 of the turbine and the rear journal bearing 12, and the gear shaft 11a of the gear train 11 is changed from the conventional one to prevent the turning device body from approaching the turbine side. The point is that it is longer. This reduces the amount of overhang at the shaft end, reduces additional weight, and is extremely advantageous against critical speeds and vibrations of the rotor.

Although this embodiment shows a rear arrangement of the turning device, the above arrangement can also be implemented in the same way if the arrangement is symmetrical to the rear arrangement.

〔Effect of the invention〕

According to this invention, since the rotor wheel is provided between the gland packing and the journal bearing, the amount of overhang at the end of the shaft is shortened, and the additional weight is also reduced, which is extremely advantageous against critical speeds and vibrations of the rotor. Ta. Furthermore, since the gear shaft is made long to keep the turning device body away from the turbine, it will not be interfered with by the exhaust section of the turbine.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing the relative position of a turning device and a turbine according to an embodiment of the present invention;
FIG. 2 is a schematic diagram showing the relative position of a turning device and a turbine according to the prior art. 2: Turbine rotor, 4: Front journal bearing, 5: Rear journal bearing, 8, 9: Gland packing, 10: Turning device main body, 11: Gear train, 12: Rotor wheel.

Claims (1)

[Claims] 1. In a turning device in which a turning rotor wheel is attached to a turbine rotor supported by a journal bearing and connected to this rotor wheel via a gear train, this rotor wheel is connected between the journal bearing and the gland packing part of the turbine. A turning device for a steam turbine, comprising: a turning device for a steam turbine;